U.S. Provisional Application No. 61/277,758, filed Sep. 29, 2009, is incorporated herein by reference in its entirety.
With the demand for energy contained in biomass such as corn cobs, demand for equipment to harvest the biomass has increased dramatically. This has thus created a need for modifications to equipment that has existed in the marketplace, as well as for completely new equipment. Some of the challenges that must be overcome include the loading, moving, transporting and refining the harvested biomass. Additionally, in some instances, it may be desired that some of the biomass created in a harvesting operation be returned to the field. This can be for any of a number of reasons, including, but not limited to, to prevent erosion, to break down and return nutrients to the field, and because those aspects of the biomass are insufficiently valuable to justify costs of collection, storage and/or transportation to a user.
Particularly with regard to corn, there is a great deal of biomass material other than the corn kernels that has to be handled. This biomass other than corn kernels is also referred to as material other than grain or MOG. Such biomass can include shucks or husks that wrap about the corn ears, leaf trash from the corn stalks, as well as the stalks themselves. This biomass is typically considered not valuable or desirable. In contrast, the corn cobs are considered valuable, both as animal feed, and as sources of oil and fuel.
As an example, presently, there is an increased demand for corn cobs as a feedstock for cellulosic ethanol, as well as other uses. As a result, there is heightened interest in collecting corn cobs during corn harvest. However, there is also concern by some that cob collection may reduce soil nutrient content. In this regard, crop residue or stover, e.g., corn stalks, leaves, husks and cobs, are traditionally left on the field after harvest, and break down over time to replenish soil nutrients. If a component of the stover, e.g., cobs is instead collected, nutrient levels could be lowered as a result. To mitigate this concern, some consider it desirable when collecting cobs, to collect mostly only cobs, that is, clean cobs with substantially all loose residual husks, leaves and stalks removed, and return the other stover to the field.
Numerous apparatus have been proposed for conveying and cleaning or separating cobs from the other stover or MOG. To illustrate, prior to the early 1960's, the common corn harvesting practice involved picking the ears of corn in the field, removing husks from the ears, and transporting the ears still containing the corn kernels to a corn crib, and later shelling the corn off of the cobs at a stationary sheller. This harvesting procedure has been almost entirely replaced by modern self-propelled combine type harvesters, which separate and collect the corn kernels, and discharge the cobs and other stover onto the field.
Combines which harvest the corn and separate the kernels from the cobs and other stover or residue, then discharge the cobs and other stover onto the field, are now the industry standard. More recently, devices for collecting cobs discharged from combines have been developed. Several of such known devices have variously utilized a towed cart or wagon for receiving and holding the cobs, and a conveyor system for conveying the cobs from the combine to the cart or wagon. Some of the cob collection devices also include apparatus for separating the cobs from the other stover or residue, mainly using air flow.
Essentially, known cob collection devices, sometimes referred to as cob caddies, include apparatus to move or convey the cobs and other residue material to a cleaning area of the device and let it fall. As the material is falling a large fan pulls air up through the material to lift the unwanted MOG or residue away from the cobs. This unwanted material is then sucked into the fan, passes through the fan and is blown out onto the ground. Reference in this regard, Flamme U.S. Pat. No. 5,941,768, issued Aug. 24, 1999, which discloses a cob collection unit pulled behind a combine to collect on a first conveyor all the residue discharged from the combine, with a separation unit behind the conveyor including a second conveyor, and utilizing a fan to suck the stover from the cobs as they are released from the top of the second conveyor and to blow the stover back onto the field. Shortcomings of these systems, however, include high power consumption, and lack of an ability to satisfactorily evenly distribute the cobs and remaining other material in the collection device.
Other known devices and systems use positive pressure air flow for separation and cleaning. Reference in this regard, Redekop et al. U.S. Patent Publication Nos. 20090095662 published Apr. 16, 2009; 20090104952 published Apr. 23, 2009; and 20090124309 published May 14, 2009, which variously disclose a pulled cob collection unit, which utilizes a sequential series of inclined belt conveyors, and blower or suction fans for directing air through the discharged material as it falls from the upper end of one conveyor onto a lower end of the next conveyor, such that the heavier cobs are to continue to the next conveyor and the lighter stover or residue will be carried away by the air flow, with the cobs being conveyed or propelled into a collection tank by a further conveyor or conveyors.
Reference also Stukenholtz U.S. Pat. No. 6,358,141 issued Mar. 19, 2002, and Redekop et al. U.S. Pat. No. 7,717,778, which disclose cob collection systems on a combine which utilize on-board bins and cob separation using sieves on the combine itself.
As a general shortcoming of known conveying and cleaning or separating devices using positive pressure, most essentially require a mat of material moving at a rather high rate of speed, and the air to move through the mat. The high speed of movement makes removal of the unwanted residue difficult. Also, a high rate of speed requires more air, whereas with a lower speed less air is required. These devices can also suffer from the shortcoming of unevenly distributing the cobs and remaining other material in the collection device. In this latter regard, when conveying or propelling the cobs and any remaining residue or MOG into the collection tank or device, the weight and size difference between cobs, which are relatively heavy and large, and the other residue or MOG, which is typically smaller and/or lighter, much of which has a paper like consistency, makes even filling difficult. Essentially, it has been found that the cobs are denser and as a result can be propelled or thrown a greater distance than the less dense residue, e.g., shucks or husks, leaf trash, and fragments. With this in mind, to achieve more even distribution, one must provide a means to throw the material very hard to overcome the lightness of the shucks, husks, etc.
Thus, what is sought is a biomass feed system adapted for feeding desired biomass, e.g., cobs, to a collection device, which also provides a capability for cleaning or removing at least some of the other, lighter or less dense biomass residue from the heavier or denser biomass to be collected, is able to more evenly distribute the biomass in the collection device, and overcomes one or more of the shortcomings set forth above.